This invention relates to a rear projector and, more particularly, to a rear projector having an angled mounting frame for securing a screen to have a predetermined arc.
In conventional rear projectors, such as video projectors as shown in FIG. 1, a cabinet 1 includes cathode-ray tubes 2 for emitting color images to a mirror 4 which reflects the color images to a flexible display screen 6 that is secured to the cabinet by a flat mounting frame 5. Screen 6 typically is made of flexible materials in order to increase the strength and rigidity of large diameter screens which, in a rear projector, may be on the order of at least 40 inches in diameter. However, using flat mounting frame 5 to secure large diameter screens has notable disadvantages.
Since a rear projector utilizes a flexible screen, the screen 6 will arc naturally in response to differences in temperature and humidity between the inside and outside of the rear projector. The size of the arc will fluctuate as a function of changes in the temperature and humidity differences. A fluctuating arc in screen 6 is undesirable for several reasons. For example, if the arc fluctuates to a larger than desirable angle, a double-image effect of the displayed image is produced. Conversely, if the arc fluctuates to a smaller than desirable angle, the screen loses its structural rigidity and thus can be cracked easily. These disadvantages are magnified as thinner screens that improve picture quality are used.